Core drill



June 25, 1935.

B. F. BLANCHARD CORE DRILL Filed July 5, 1952 INVENTOR. Beg/'amm E 5/0/1 Chard BY l ATTORNEY.

Patented June 25, 19135 PATENT OFFICE CORE Benjamin F. Blanchard,

DRILL Brea, Calif., assigner to Union Oil Company of California, L os Angeles, Calif., a corporation of Callfornia Application July 5, 1932, Serial No. 620,833

17 Claims.

This invention relates to core drills which are commonly employed for taking core samples of the earths structure when being penetrated in connection with the drilling of oil wells and the like.

In one type of core drill a barrel which is movable with respect to the outer housing is employed for reception of the core, such inner core barrel being sometimes so mounted as to actuate core gripping dogs or jaws when it is desired to break oil the core. An object of the present invention is to mount such a core barrel so that it may be held in an elevated position during drilling to permit proper retraction of the core breaking jaws and to permit depression when desired to actuate the core breaking jaws into operative position. A further object is to insure against twisting off the ore before cutting of the core has been completed. Y 20, Primarily the invention resides in a combination oi a movable core barrel and core breaking means with a piston adapted to be actuated by the pressure of mud or other drilling fluid which is commonly circulated through the drill stem which carries the core bit. The function of this mud circulation is the proper lubrication and cooling of the drill bit and elevation and discharge of the cuttings from the well hole. In a preferred form the invention includes a spring 30 partly counterbalancing the weight of the core barrel so that the pressure of the circulating mud is*y relied upon only in part to maintain elevation of the barrel during core drilling. The invention also includes such a combination wherein the core barrel is rotatably mounted with respect to the housing for the core barrel, andif desired with respect to the piston also.- For purpose of providing a diierential of pressure between the 'two sides of the piston, the under side of the piston is connected to receive the full applied pressure of the mud passing downward through the drill stem, and the upper side of the piston is connected with the exterior of the drill stem so that only the hydrostatic head is exerted thereon.

In the accompanying drawing wherein one embodiment oi' the invention is disclosed by way of illustration:

Fig. 1 is a vertical section through a core drill constructed according to the present invention and taken approximately on the line I-I of Fig. 2; and

Figs.' 2, 3, 4 and 5 are cross sections taken respectively upon the lines 2 2, 3 3, 4 4, 5 5 of Fig. 1.

y According to the form illustrated in the draw- (Cl. Z55-72) ing a drill stem I0 is threadedly connected with an upper tubular housing element I2 which in turn is threadedly connected by means of a tool joint I4 with a lower housing element I5. The element I5 has the usual or any preferred type of core bit I6 threadedly mounted thereon. The housing I5 receives a core barrel I8 whose lower end may be beveled as shown for the purpose of engaging an annular series of core breaking dogs or jaws and forcing the same inward so that 1c they may grip a core and cause the same to be broken off as hereinafter indicated. In the form shown these jaws 20 aref pivoted in a carrier 22 which may be threaded into the bit I6 and securely retained to such position by engagement of 15 the lower end of the housing member I5 which is threaded down into said bit I6. The jaws 20 and carrier 22 also serve as a core catcher and retainer when the core,has beenbroken oil'. As shown, the lower end of core barrel I8 slidably 20 projects into the upper end of the carrier 22 and the sliding joint therebetween may be packed for the exclusion of mud as indicated. The upper end of core barrel I8 is closed by a head 24-carrying at its upper end a cage 25 containing a ball 25 check valve 26 when desired. AA rod 38 extends upward from the cage 25 through a perforated positioning disk or spider 32 whose perforations 33 permit passage of mud. The upper end of the rod is connected with the lower end of a bear- 30 ing retainer 34 which'contains a ball bearing unit 35. A piston rod 36 which is journaled in bearing projects upwardly through the retainer 34 and carries on its upper end a piston 38 adapted to reciprocate ina cylinder 4li. The rods 30 and 35 36 thus constitute a divided piston rod whose parts are connected by a rotary joint 34, 35 which does not affect the functioning of piston 38. `W'lghe cylinder 4Ilis secured to the wall ofthe housing I2 through the medium of suitable spacing lugs .40 42 which are integral with the cylinder and are `preferably welded to the wall I2 as indicated at 44. Inthis manner channels 45 are provided between cylinder and the wall of member I2 which serve to pass mud downward from the drill stem I0. 'I'he cylinder 40 is open at its lower end in order that the full mud pressure may be exerted on the underside of the piston 38,-but the upper end of cylinder 40 is closed to the mud stream as shown. However the small chamber 46 50 in said upper end of the cylinder is, connected with the vexterior of the housing member I2 through the medium of a small tube 48 through which the hydrostatic head in the well outside the drill stem is transmitted to the upper side of said piston. 55

In order to assist the mud pressure in elevatingthe piston 38 a spring 58 is disposed about the rod 38 in a position between the bearing retainer 34 and the spacer or spider 32. To provide a satisfactory abutment for the lower end of said spring 58 a suitable ball bearing 52 is mounted upon the spider 32. If required a thrust bearing 54 of suitable type may be provided on rod 38 between cage 25 and spider 32.

In operating with this structure, the core drill I3 is rotated from the surface of the well through the medium of the drill stem I8 and the usual drilling mud is circulated downward through the bore of said drill stem, past the cylinder 48 through the mud channels l5, and thence through the apertures 33 of the spider 32 into the chamber around the core barrel I8. From this chamber the mud is directed downward into the vicinity of the cutting blades of the bit I6 by way of discharge passages 55 provided in the lower end of the housing member I 5, or by way of any other form of passage suitably located to discharge the mud into the vicinity of the bit to clear and cool the latter in substantially the usual manner of operating devices of this general character. The mud head of course rises in the well hole and overflows at the surface to discharge the cuttings. The differential of pressure between'the combined head and pump pressure exerted upon the under side of the piston 38, and the lower outside head pressure exerted through the connecting tube 48 upon the top of the piston, taken in conjunction with the expansive energy of the spring 58serves to maintain the piston 38 and the. core barrel I8 in elevated position, so that the lower edge of barrel I8 is lifted out of lengagement with the core gripping dogs 28.

As the bit I8 rotates it cuts a core which moves gradually upward into the core barrel I8 past the dogs 28 and tends to force the trapped mud upward past the ball check valve 26. This core, be-

ing still integral with the rock formation at the bottom of the hole, exerts considerable friction upon the inner walls of the core barrel I8 tending to prevent the relative rotation of said core barrel I8 with respect to the housing I5. Where this diiliculty is not overcome there isfa further tendencyv to twist o ff the core instead of allowing it to remain intact. 'Ihis diiculty however is overcome by reason of the rotary joint provided between the rods 38 and 36 by the bearing 3l, 35 which permits relative rotation between these parts. This rotation is also facilitated by the ball bearing structure at 52, and of course the rod 38 rotates freely in the central hub of spider 32. The lower end of core barrel I8 also rotates freely in the packed extension of the carrier 22. In this manner'during drilling there is no interference with the functioning of the piston 38 which vis maintained in elevated position under the inuence of the mud pressure and may remain in relatively stationary or non-rotative relation with respect tothe rotating drill stem I8 and the housing I2.

When a core has been cut sufficiently long to fill the barrel I8, the pump pressure on the circulating mud iscut off with the result that the pressures above and below the piston' 38 are equalized. Possibly, if the core barrel I8 and associated parts are-heavy enough, they Will settle Somewhat against the spring 58 thus causing the beveled lower edge of the core barrel I8 to engage the upper ends of the core breaking jaws 28 and swing them into engagement with the walls of the core. Qr, if the core barrel does not settle by gravity, elevation of the whole structure through the medium of the drill stem I8 Will result in the exertion of longitudinal friction between the core and the core barrel sufficient to move the core barrel I8 downward with respect to the housing I and the jaws 28 as the latter are elevated, with the result that the beveled lower edge of the core barrel I8 positively forces the jaws 28 into engagement with the sides of the core. Further elevation of the structure forces said jaws into the core until the core is broken cgi at the point where the jaws penetrate. The core will then settle down upon the jaws forcing them into a horizontal position, and as a consequence said jaws together with the carrier 22 act as a core catcher which supports the core and retains it within the barrel I8 until elevated to the surface of the well.

From the foregoing it will be apparent that the present structure makes it possible to rely upon the pressure of the circulated mud as a medium for maintaining elevation of a core barrel in an uppermost position during core drilling and for actuation of the core barrel into a lowermost position for core breaking purposes when desired to recover the core, the latter function being accomplished simply by removal of pump pressure from the mud. At the same time the present invention permits relative rotation of the core barrel with respect to the drill stem without any interference with the functioning of the piston and while maintaining elevation of the core barrel.

It is to be understood that the present disclosure is merely illustrative of the generic invention, and ythat many variations within the skill of the average mechanic may be developed which will fall within the range of the appended claims.

I claim:

1. A core drill comprising a rotatable housing carrying a core bit on its lower end, a corev breaker and catcher positioned within the bit adjacent its lower end, a core barrel cooperating with said breaker and catcher to receive a core, a piston connected with said core barrel, a cylinder carried by said housing and receiving said piston, said housing and cylinder having means for transmitting circulated mud pressure to one end of the cylinder for maintaining the piston and core barrel in an elevated position.

2. A structure according to claim 1 and a pressure transmitting connection extending between the cylinder on the other'side of the piston and the exterior of said housing. l

3. A structure according to claim 1 wherein rod connects the piston and core barrel and the rod is divided and a rotatable joint interposed therein.

4. A core drill comprising a rotatable drill stem, a housing carried thereby, a core bit carried by said housing, a core barrel mounted within the housing, and a piston carried by the core barrel and adapted to be moved to elevated position under influence of fluid pressurel supplied to said housing. y

5. A structure according to claim 4A wherein a core breaker is carried by the housing and is actuable through the medium of the core barrel.

6. A structure according to claim 4 wherein a rotatable joint connects the piston with the core barrel toL permit relative rotation.

'7. A structure according to claim 4 wherein a maintaining its elevation.

noname 8. A structure according to claim 1 wherein a spring is associated with the piston. to assist in maintaining its elevation.

9. A structure according to claim d wherein a rod connects the piston with the core barrel, a rotatable Joint interposed with said rod and a spring connected with said rod to assist the piston in maintaining the core barrel in elevated position.

10. A core drill comprisinga housing adapted for the circulation of iiuid under pressure therethrough, a core blt carried by the lower end of said housing, a core barrel disposed within said housing, a cylinder provided in said housing and a piston mounted within said cylinder and con'- nected with said core barrel, said piston being positioned to receive the pressure of the circulated uid, on one'side and being adapted to be moved into elevated position under the influence of said pressure.

11. A structure according to claim l and a connection between the cylinder at the other side of the piston and the exterior of the housing.

12. A structure according to claim wherein a core breaker is carried in the housing and ls actuable through the agency of the core barrel.

13. A structure according to claim 10 and a rotatable joint between the piston and the core barrel permitting relative rotation between the piston and the core barrel.

14. A core drill comprising a housing, a core barrel reciprocably I mounted therein, a core breaker associated with said barrel and actuable thereby when in a lower position, means for supplying a iluid under pressure to the housing, and means connected with the core barrel and actuable by said uid pressure to elevate the core barrel.

15. A core drill comprising a housing, a core barrel mounted within the housing, a core breaker in the housing, a cylinder within the housing, a piston associated with the core breaker and movably mounted in said cylinder, means associated with the piston for actuation of the core breaker to breaking position, means connecting one side o1' the piston with the exterior of the housing, and means to supply iluid under pressure to the other side of the piston to move said piston for operation of the means for actuating the core breaker.

16. A structure according to claim wherein the housing contains a passage through which the pressure fluid is conducted downward therethrough to supply the drill and the piston.

17. A core drill comprising a housing, a core barrel mounted therewithin, a core breaker associated with said core barrel, a piston directly connected with said core barrel, a cylinder receiving said piston and mounted within said housing, means in said housing connecting one side of the piston with the exterior of the housing and the other side of said piston with the interior of the housing for transmission of corresponding pressures, and means to supply lluid pressure to the piston to maintain the piston and core barrel in predetermined position with respect to the core breaker.

BENJAMIN F. BLANCHARD. 

